Traffic displays and other display surfaces have long been provided with electric lighting for nighttime, special effects and other illumination. Examples include overhead traffic displays with directional signs, highway speed, exit or other markings, or billboard or other advertisements. While such lighting has been well known, still the use and installation of such fixtures, including the mounting structure or "luminaires" for the light bulbs themselves, has not always been easy, safe or convenient.
For instance, a typical traffic display might be provided with a plurality of luminaires running along the bottom ledge of the display support structure, to provide evenly distributed lighting across the display surface. However, when a bulb burns out and requires replacement, which may be on the order of every 18 months for a conventional bulb, typically 250 or 400 watts, it may not be easy for a workman to ascend the traffic display structure and gain access to the deficient bulb.
This is especially true for traffic displays which are installed close to, or as is often the case, completely overhanging, the highway. In such installations, the workman may actually have to climb a ladder, "cherry picker" or other support set up at the edge of, or over into, the highway itself to reach the deficient bulb. Repair work under those circumstances of course runs the danger of workmen being put in or over the path of traffic, or the possibility of tools, bulbs or other material being dropped into traffic's way.
In addition, repair in this fashion is expensive, involving costs which can begin at a few thousand dollars including workman time, vehicles, material, costs associated with lane closings, and other costs.